The importance of cytokines in rheumatic diseases is illustrated by: 1) animal studies that demonstrate an important role for IL-1beta and TNF- alpha in collagen-induced arthritis, down-regulation of collagen-induced arthritis by IL-10 and IL-4, and suppression of murine systemic lupus erythematosis by TNF-alpha; and 2) human studies that demonstrate the efficacy of TNF-alpha antagonists in the therapy of rheumatoid arthritis. The Cytokine Quantitation Core will facilitate studies of the roles of cytokines in rheumatic and related immune disorders by making available to members of the research base: a unique assay that allows measurement of in vivo cytokine production real-time PCR for measuring cytokine gene expression a new technique for identifying cytokine-secreting cells without killing these cells standard techniques for cytokine measurement, such as cytokine ELISAs and RNAse protection assays. Research base members have already collaborated on the use of some of these assays to study: 1) the roles of IL-2 and IFN-gamma in the regulation of collagen-induced arthritis; 2) TGF-beta regulation of disease in murine models of SLE; 3) IL-4 and IL-10 regulation of human juvenile rheumatoid arthritis; 4) cytokine regulation of host protection against gastrointestinal nematode infections; and 5) regulation of type 2 cytokine responses. The Core will facilitate ongoing collaborations in studies of rheumatic diseases by; increasing the efficiency and economy of apply presently available techniques; promoting the use of these techniques by core group members; and supporting further development and dissemination of novel and improved techniques for measuring cytokine secretion and cytokine gene expression.